As a flexible, high-efficiency and high-precision automatic machine tool, a NC machine tool can comparatively well solve complex, precise, small-amount or multi-type machining problems, and is generally composed of a NC system, a main body and other auxiliary devices. The NC system being a core of the whole NC machine tool is capable of integrating position (trajectory) control, speed control and torque control altogether, executing parts of or whole NC functions according to code instructions, and realizing motion control of one or more machineries. As shown in FIG. 1, a NC system normally includes an input/output device, a NC device, a programmable logic controller (PLC), a servo system, a detection and feedback device and the like, amongst which the NC device is a hard core of the NC system.
The NC device may include a display module, an input/output module, a decoder, a motion planner, an axis motion controller, a memory and the like. The display module is an important medium for human-machine interaction, and provides a visual operation environment for users. The input/output module is an interface for data and information exchange between the NC device and an external device, and is mainly used for inputting data such as NC machining programs, control parameters, compensation quantities and the like, and for outputting information such as servo drive, trajectory control and the like. The decoder is mainly used for decoding program segments of the NC machining program. The motion planner mainly facilitates speed processing and interpolation operation. The axis motion controller is an interface module between the NC device and a servo drive system and operates for position control. The memory is used for storing information such as machining programs, system configuration parameters, system inherent data and the like.
At present, a conventional mainstream high-grade NC system normally employs an architecture formed by an upper computer for handling non-real-time tasks and a lower computer for handling real-time tasks such as motion control and logic control. The architecture is extremely well applied to the numerical control field, communication between the upper computer and the lower computer and control thereof are comparatively easily realized, and the NC system based on the architecture possesses a distributed characteristic and partly supports secondary research and development by users and independent upgrading. In the architecture of a conventional NC system, the upper computer and the lower computer are both installed in the vicinity of a machine tool and are respectively provided with an industrial personal computer thereby being communicated with each other via the industrial personal computers in connection through a bus or a network, as shown in FIG. 2.
According to the current situation of the NC machining field that user requirements for functions and performances of the NC system are more and more high, conventional architectures formed by a single computer or by an upper computer and a lower computer both face the same challenge: how to improve the performances and the service capability of the NC system while keeping or reducing production cost. In recent years, increasingly complex computation process and integration demands of intelligent functions raise higher requirements for kernel and memory of a NC device and cause production cost rising pressure. The conventional architecture formed by the upper computer and the lower computer partly increases exploitation and upgrading difficulties of the NC system and blocks development of the NC system. Furthermore, complex functions of the NC system cannot be effectively utilized by an operator of a machine tool in a noisy chaotic environment of a workshop, which correspondingly causes resource waste and influences production efficiency of enterprises.
Therefore, the present conventional architecture formed by the upper computer and the lower computer causes the intelligent technology of the NC system to difficulty adapt to a more and more complex manufacture process, becomes a main bottleneck during development of the NC system towards intelligence, digitalization and multi-functionalization, and brings great difficulty for improving performances of the NC system.
The applicant's Chinese patent publication No. CN104298175A discloses a virtualization-based NC system, and the NC system comprises a local NC device and a remote server connected to each other. The remote server is used for providing high value-added functions for the NC system, such as rapid programming, data acquisition and processing, G code quality analysis and optimization, and the like, and also for handling a part of non-real-time tasks in a conventional NC system comprising an upper computer and a lower computer, such as decoding, machining simulation, input/pretreatment and the like. The server is connected with the NC device via a remote desktop client disposed on the NC device, and the client enables an operator to conduct virtual operation on the server via a human-machine interactive device (HMI) of the NC device by using virtualization technology, thereby remotely controlling and operating the server and facilitating usage of intelligent software service and NC machining control by cooperation of the server and the NC device.
In the above-mentioned technical scheme, the remote server is employed for providing high-end intelligent functions for the NC system and also for handling a part of non-real-time tasks originally processed by the upper computer in the conventional NC system, thereby improving the service capability of the NC system and the machining performance. However, the NC system still employs a conventional architecture formed by the upper computer and the lower computer and does not break through the conventional architecture since only a server is added for providing third-party services for the NC system. Although partly expanding functions of the NC system, the architecture still has many defects: firstly, as majority of computation related to machining (such as interpolation, speed planning and the like) is facilitated locally, machining performance and efficiency of the NC system are not greatly raised; secondly, because HMI is arranged locally, an operator must conduct NC machining operation in the field and correspondingly extensively-demanded remote machining control is greatly limited; and thirdly, function exploitation and performance raising of HMI are limited by local software and hardware resources and development of the NC system is severely restricted since the HMI is integrated on the local NC device.